Do the new triatomine species pose new challenges or strategies for monitoring Chagas disease? An overview from 1979-2021

Chagas disease persists as one of the most important, and yet most neglected, diseases in the world, and several changes in its epidemiological aspects have been recorded since its discovery. Currently, some of the most relevant changes are related to: (i) the reduction in the incidence of the endemic due to the control of the most important vectors, Triatoma infestans and Rhodnius prolixus, in many countries; (ii) the migration of human populations spreading cases of the disease throughout the world, from endemic to non-endemic areas, transforming Chagas disease into a global threat; and (iii) new acute cases and deaths caused by oral transmission, especially in the north of Brazil. Despite the reduction in the number of cases, new challenges need to be responded to, including monitoring and control activities aiming to prevent house infestation by the secondary vectors from occurring. In 1979, Lent & Wygodzinsky(1) published the most complete review of the subfamily Triatominae, encompassing 111 recognised species in the taxon. Forty-two years later, 46 new species and one subspecies have been described or revalidated. Here we summarise the new species and contextualise them regarding their ecology, epidemiologic importance, and the obstacles they pose to the control of Chagas disease around the world.

Homogeneidade cromossômica em diferentes populações de Panstrongylus megistus do Brasil / Chromosome homogeneity in different populations of Panstrongylus megistus of Brazil

Os triatomíneos são insetos vetores do protozoário Trypanosoma cruzi, agente etiológico da doença de Chagas. Existem seis espécies de maior importância vetorial, a saber, Triatoma infestans, Panstrongylus megistus, T. brasiliensis, T. sordida, T. pseudomaculata e Rhodnius neglectus. P. megistus apresenta grande distribuição geográfica e já foi coletada em 22 Estados brasileiros. Variações cromossômicas intraespecíficas já foram detectadas na subfamília Triatominae. Assim, o presente trabalho teve como objetivo analisar as características cromossômicas de P. megistus provenientes de sete diferentes Estados brasileiros (Rio Grande do Norte, Rio Grande do Sul, Paraná, São Paulo, Minas Gerais, Bahia e Santa Catarina), por meio de técnicas citogenéticas clássicas. Todos os insetos analisados apresentaram as mesmas características cromossômicas: 21 cromossomos, sistema de determinação do sexo do tipo X1X2Y, tamanho relativo dos autossomos com pequena variação, tamanho relativo dos cromossomos sexuais (Y>X1>X2), cromocentro na prófase meiótica formado apenas pelos cromossomos sexuais e presença de heterocromatina apenas no cromossomo sexual Y. Sendo assim, o presente trabalho apresenta dados evolutivos sobre as populações de P. megistus do Brasil, demonstrando que as populações de diferentes Estados brasileiros apresentam homogeneidade cromossômica.(AU)

The triatomines are insects vectors of the protozoan Trypanosoma cruzi, etiologic agent of Chagas disease. There are six species of greatest importance vector, out more, Triatoma infestans, Panstrongylus megistus, T. brasiliensis, T. sordida, Rhodnius neglectus and T. pseudomaculata. P. megistus presents great geographic distribution and has been collected in 22 Brazilian states. Intraspecific chromosomal variations have been detected in Triatominae. Thus, the present study aimed to analyze the chromosomal characteristics of P. megistusfrom seven different Brazilian states (Rio Grande do Norte, Rio Grande do Sul, Paraná, São Paulo, Minas Gerais, Bahia and Santa Catarina) by means of classical cytogenetic techniques. All insects analyzed showed the same chromosomal characteristics: 21 chromosomes, sex determination system the type X1X2Y, relative size of autosomes with little variation, relative size of the sex chromosomes (Y>X1>X2), chromocenter in meiotic prophase formed only by sex chromosomes and the presence of heterochromatin only in sex chromosome Y. Thus, this paper presents evolutionary data on the populations of P. megistus of Brazil demonstrating that populations from different Brazilian states have chromosomal homogeneity.(AU)

Chromosomal characteristics and distribution of constitutive heterochromatin in the Matogrossensis and Rubrovaria subcomplexes.

Since 1966 the triatomines were grouped in complexes and specific subcomplexes. Although the complex and subcomplexes not have taxonomic importance, should be monophyletic groups and cytogenetic tools have proved to be of great importance to characterize these species groupings. Based on this, this paper aims to describe the chromosomal characteristics and heterochromatic pattern of Matogrossensis and Rubrovaria subcomplexes, in order to contribute to the taxonomic and evolutionary relationships of these vectors. In this study, at least three males from each species (Triatoma baratai, Triatoma costalimai, Triatoma guazu, Triatoma jurbergi, Triatoma matogrossensis, Triatoma vandae, Triatoma williami, Triatoma carcavalloi, Triatoma circummaculata, Triatoma klugi, Triatoma pintodiasi and Triatoma rubrovaria) were analyzed by means analyzed by means of cytogenetic techniques of C-banding. All species showed the same cytogenetic characteristics: 22 chromosomes, low variation in the size of autosomes, sex chromosome Y larger than X, initial prophase composed of only one heterochromatic chromocenter formed by the sex chromosomes X and Y (except for T. pintodiasi that presented the sex chromosomes individualized during all stages of prophase) and presence of constitutive heterochromatin restricted to sex chromosome Y. These characteristics, although common to Matogrossensis and Rubrovaria subcomplexes allow to distinguish these species of species grouped in most of South America subcomplexes, as Brasiliensis, Maculata, Sordida and Insfestans. Thus, the cytogenetic analysis was of extreme importance to differentiate both subcomplexes of the other subcomplexes of South America. However, probably due to evolutionary proximity existing between these subcomplexes was not possible to observar species differences that make up the Matogrossensis subcomplex of the Rubrovaria subcomplex. Therefore, we emphasize that new comparative analyzes, as experimental hybrid crosses and molecular cytogenetic analysis are necessary to clarify the evolutionary relationship between these important subcomplexes of vectors.

Coloration of the testicular peritoneal sheath as a synapomorphy of triatomines (Hemiptera, Reduviidae) / Coloração da bainha peritoneal testicular como uma sinapomorfia dos triatomíneos (Hemiptera, Reduviidae)

Recently, were described some morphological characteristics of 18 species of terrestrial hemipteran grouped in the Alydidae, Coreidae, Corimelaenidae, Lygaeidae, Rhopalidae, Scutelleridae, Tingidae and Reduviidae family that presented found variation in coloration of testicular peritoneal sheath (Reddish, Orange, Yellowish or Transparent). Thus, this study aims to analyzed the coloration of the peritoneal sheath in 44 species of triatomines grouped in nine different genera, with the aim of analyze whether the insects of the Triatominae subfamily also show variations in coloration. By means of analysis of the sheath was possible to observe that members of this subfamily have no interspecific differences, because all species have a transparent sheath. Thus, this paper describes the coloring of the peritoneal sheath in 44 species of the subfamily Triatominae and mainly suggests that the transparent color is one synapomorphy of this important group of insect vectors.

Recentemente, foram descritas algumas características morfológicas de 18 espécies de hemípteros terrestres agrupados nas famílias Alydidae, Coreidae, Corimelaenidae, Lygaeidae, Rhopalidae, Scutelleridae, Tingidae e Reduviidae que apresentaram grandes variações na coloração da bainha peritonial testicular (avermelhada, alaranjada, amarelada ou transparente). Assim, este estudo teve como objetivo analisar a coloração da bainha peritoneal em 44 espécies de triatomíneos agrupadas em nove gêneros diferentes, com o intuito de analisar se os insetos da subfamília Triatominae também apresentam variações na coloração da bainha. Por meio da análise da bainha, foi possível observar que os membros desta subfamília não apresentaram diferenças interespecíficas, pois todas as espécies analisadas possuem bainha transparente. Assim, o presente trabalho descreve a coloração da bainha peritoneal em 44 espécies da subfamília Triatominae e, principalmente, sugere que a cor transparente é uma sinapomorfia deste importante grupo de insetos vetores.